THE SKELETON IN REPTILES. THE STERNUM. 

 THE STERNUM. 



287 



A sternum occurs in the following groups of reptiles : 

 Rhynchocephalia, nearly all Lacertilia, Pythonomorpha, Croco- 

 dilia, and Pterosauria, and is generally more or less rhomboidal 

 or shield-shaped. In Pterosauria it is keeled and bears some 

 resemblance to that of birds. It may have been replaced by 

 membrane bone. 



The sternum is absent in Sauropterygia, Ichthyosauria, 



FIG. 54. VENTRAL VIEW OF THE SHOULDER-GIRDLE or STERNUM OF A 

 LIZARD (Loemanctus longipes] x 2. (After PARKER.) 



1. interclavicle. 



2. clavicle. 



3. scapula. 



4. coracoid. 



5. precoracoidal process. 



6. glenoid cavity. 



7. sternum. 



8. xiphisternum. 



9. sternal rib. 



